Synthesis of 3D-Rich Heterocycles: Hexahydropyrazolo[1,5-a]pyridin-2(1H)-ones and Octahydro-2H-2a,2a1-diazacyclopenta[cd]inden-2-ones

Kirar, Eva Pušavec; Drev, Miha; Mirnik, Jona; Grošelj, Uroš; Golobič, Amalija; Dahmann, Georg; Požgan, Franc; Štefane, Bogdan; Svete, Jurij

doi:10.1021/acs.joc.6b01608

Cited by 9 publications

(6 citation statements)

References 51 publications

(55 reference statements)

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“…In the absence of firm experimental and theoretical proofs, the generally accepted plausible mechanism is based on the catalytic Cu(I) acetylide as the reactive species, which undergoes cycloaddition, followed by protonation of the cuprated cycloadduct. 22,24,28,29,31,[33][34][35]37,38,42,45,46 This reaction pathway is supported by experiments performed with copper(I) acetylides, deuterated acetylenes, and/or proton sources, such as D 2 O and AcOD. 29,[33][34][35]38 Copper(I) was, either used directly, 29,33 or formed in situ by reduction of Cu(II) 34,35 or by oxidation of Cu(0).…”

Section: The Mechanism Of the Cuaiac Reactionmentioning

confidence: 92%

“…fully unsaturated achiral pyrazole derivatives with the use of hydrazones 16,17 and sydnones [40][41][42][43][44][45][46][47] as 1,3-dipoles and even metal-free reactions can be regio-and stereoselective. 7,8,[49][50][51][52] Another difference between the reactions is in the catalyst scope, which is broader with CuAIAC which is catalyzed by Cu(I) and Cu(II), while CuAAC is catalyzed only by Cu(I)-species (cf.…”

Section: Syn Thesismentioning

confidence: 99%

“…In the presence of CuI and DIPEA, however, dipoles 129 reacted smoothly at room temperature to furnish 130 in 47-53% yields, respectively (Scheme 40). 45…”

Section: Syn Thesismentioning

confidence: 99%

“…Presumably the most appropriate mechanistic definition of CuAIAC would be, that CuAIAC is an asynchronous, but still concerted [3+2]-cycloaddition reaction. 45 A generally accepted concerted mechanism of CuAIAC reaction is shown in Scheme 46 (Path A).…”

Section: The Mechanism Of the Cuaiac Reactionmentioning

confidence: 99%

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Copper-Catalyzed Azomethine Imine–Alkyne Cycloadditions (CuAIAC)

Grošelj

Požgan²,

Štefane³

et al. 2018

Synthesis

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Although the first example of copper-catalyzed azomethine imine–alkyne cycloaddition (CuAIAC) was published only a year after the seminal papers of Meldal and Sharpless on Cu-catalyzed azide–alkyne cycloaddition (CuAAC), the CuAIAC reaction has remained overlooked by the synthetic community for almost a decade. Since 2010, however, CuAIAC reaction started to emerge as a promising supplement to the well-known CuAAC reaction. The present review surveys primarily the literature on CuAIAC reaction since 2003. Beside this, azomethine imine–alkyne cycloadditions catalyzed by other metals, selected examples of metal-free reactions, and related [3+3] and [3+4] cycloadditions of azomethine imines are presented. All these experimental data indicate the viability of CuAIAC in organic synthesis and the applicability in ‘click’ chemistry.1 Introduction2 Reactions with Acyclic Azomethine Imines3 Reactions with C,N-Cyclic Azomethine Imines4 Reactions with N,N-Cyclic Azomethine Imines5 Reactions with C,N,N-Cyclic Azomethine Imines6 The Mechanism of the CuAIAC Reaction7 Conclusions and Outlook

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Section: The Mechanism Of the Cuaiac Reactionmentioning

confidence: 92%

Section: Syn Thesismentioning

confidence: 99%

“…In the presence of CuI and DIPEA, however, dipoles 129 reacted smoothly at room temperature to furnish 130 in 47-53% yields, respectively (Scheme 40). 45…”

Section: Syn Thesismentioning

confidence: 99%

Section: The Mechanism Of the Cuaiac Reactionmentioning

confidence: 99%

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Copper-Catalyzed Azomethine Imine–Alkyne Cycloadditions (CuAIAC)

Grošelj

Požgan²,

Štefane³

et al. 2018

Synthesis

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“…Additionally to the annulation reaction pathways of N,N -cyclic azomethine imines, their direct functionalization afforded alternative modes of supplementing the library of dinitrogen-fused heterocycles. Based on the electrophilic character of the iminium moiety, nucleophilic additions to N,N -cyclic azomethine imines, including asymmetric Rh-catalyzed arylation [18], cyanation [19] Grignard reagent addition [20,21], and trifluoromethylation [22], have been introduced to functionalize dinitrogen heterocycles.…”

Section: Introductionmentioning

confidence: 99%

Eosin Y-Catalyzed Visible-Light-Mediated Aerobic Transformation of Pyrazolidine-3-One Derivatives

et al. 2020

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By utilizing an underexplored reactivity of N1-substituted pyrazolidine-3-ones, we developed a visible-light-induced aerobic oxidation of N1-substituted pyrazolidine-3-one derivatives yielding the corresponding azomethine imines. The resulting azomethine imines can be further reacted with ynones in situ under copper catalyzed [3 + 2] cycloaddition reaction conditions yielding the corresponding pyrazolo[1,2-a]pyrazoles in good yields. The methodology can be extended to other 1-aryl-substituted pyrazolidinones which undergo endocyclic oxidation deriving the corresponding pyrazolones as single products.

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[3 + 2] Cycloadditions of Azomethine Imines

Grošelj

Svete

2020

Organic Reactions

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In spite of their late discovery in the middle of 20 th century, the importance of azomethine imines and their [3+2] cycloaddition reactions has grown constantly throughout the decades. Today, [3+2] cycloadditions of azomethine imines have become indispensable in the preparation of pyrazole derivatives with all degrees of saturation. The structural diversity of azomethine imines is wide and comprises acyclic, C , N ‐cyclic, N , N ‐cyclic, and C , N , N ‐cyclic 1,3‐dipoles. Although electron‐deficient dipolarophiles are preferred, electron‐rich dipolarophiles, such as enol ethers and enamines, are also commonly used in these reactions. Compared to cyclocondensation methods and [3+2] cycloadditions with diazoalkanes and nitrile imines, [3+2] cycloadditions with azomethine imines provide access to a greater diversity of pyrazole derivatives with all degrees of saturation. As with other 1,3‐dipolar cycloadditions, a concerted and nearly synchronous mechanism has been proposed for most [3+2] cycloadditions of azomethine imines, although a stepwise mechanism may be viable in some cases. Several examples of asymmetric [3+2] cycloadditions of azomethine imines that afford non‐racemic cycloadducts with high enantioselectivity have been reported. These asymmetric cycloadditions are performed with various types of transition metal catalysts and organocatalysts, and indicate their potential for the asymmetric synthesis of saturated pyrazole derivatives. Finally, many examples of copper‐catalyzed and thermal, strain‐promoted [3+2] cycloadditions of azomethine imines (in particular sydnones) clearly indicate wide applicability of these reactions in bioconjugation, fluorescent labelling, materials functionalization, and other applications outside the realm of pure organic synthesis.

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Synthesis of 3D-Rich Heterocycles: Hexahydropyrazolo[1,5-a]pyridin-2(1H)-ones and Octahydro-2H-2a,2a¹-diazacyclopenta[cd]inden-2-ones

Cited by 9 publications

References 51 publications

Copper-Catalyzed Azomethine Imine–Alkyne Cycloadditions (CuAIAC)

Copper-Catalyzed Azomethine Imine–Alkyne Cycloadditions (CuAIAC)

Eosin Y-Catalyzed Visible-Light-Mediated Aerobic Transformation of Pyrazolidine-3-One Derivatives

[3 + 2] Cycloadditions of Azomethine Imines

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